Starting thread control mechanism



Nov. 27, 1962 s. J. KETTERER STARTING THREAD CONTROL MECHANISM 5 Sheets-Sheet 1 Filed Aug. 24, 1961 ws.- :i

INVENT OR SrA/VLEY J KETTERER Nov. 27, 1962 y s. J. KETTERER 3,065,718

STARTING THREAD CONTROL MECHANISM Filed Aug. 24, 1961 5 Sheets-Sheet 2.

STANLEY J. KETTERER B Y WITNESS Wyqvy NOV. 27, 1962 s, J, KETTERER 3,065,718

STARTING THREAD CONTROL MECHANISM Filed Aug. 24, 1961 5 Sheets-Sheet 3 INVENTOR. STANLEY J. KETTERER BY @MM /wJ ATTORNEY WITNESS United States Patent Oilice bll Patented Nov. 27, 1962 3,0d5,713 STARTING TI-mEAD CNTRGL ME'CHANESM Stanley J. Ketterer, Morris Plains, NJ., assigner to The Singer Manufacturing Company, Elizabeth, NJ., a corporation of New Jersey Filed Aug. 24, 1961, Ser. No. 133,693 3 Ciairns. (Cl. 112-1310 This invention relates to cyclically operated lock stitch sewing machines of the type in which the needle and looptaker, while partaking of motion in timed relation suitable for the formation of lock stitches, are in the alternative capable of cooperating to effect the replenishment of a supply of locking thread on a bobbin in place in the loop-taker from the needle thread supply. More partie ularly, this invention relates to a novel and improved means for controlling the length of the starting end of the needle thread which is wound on the bobbin in place in the loop-taker.

It is an object of this invention to provide, in a lock `stitch sewing machine of the above character, a novel and improved stop motion mechanism by which the position of the needle thread take-up mechanism when the sewing machine is at rest may be determined accurately so that the starting end of the needle thread may be shortened an accurately metered amount at the start of each sewing machine operating cycle.

With the above and additional objects and advantages in View as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a vertical cross-sectional view of a sewing machine having this invention supplied thereto,

FIG. 2 represents an enlarged vertical cross-sectional view of the loop-taker of the sewing machine of FIG. 1 illustrating the manner in which the starting end of the needle thread is clamped in place on the loop-taker beak to initiate replenishment of thread on the bobbin,

FIG. 3 is an enlarged cross-sectional View of the stop motion mechanism taken substantially along line 3 3 of FIG. 1,

FIG. 4 represents an enlarged head end elevational View of the sewing machine of FIG. l with the bracket arm land cover plate removed and portions of the bracket arm broken away clearly to illustrate the thread path to the take-up mechanism and the needle and,

FIG. 5 is an enlarged elevational view of a portion of the stop motion device illustrating the separable frictional driving device in driving relation.

The embodiment of the invention illustrated in the accompanying drawings discloses a lock stitch sewing machine in which the under or locking thread may be replenished on the bobbin in place in the loop-taker during interrelated motion of the needle and loop-taker suitable for the formation of lock stitches substantially as described in detail in the copending United States application of Stanley I. Ketterer and William l. Edwards, Serial No. 15,955, tiled March 18, 1960. Theembodiment illustrate'd in the accompanying drawings also includes a means for severing the sewing threads and clearing the bobbin of unused locking thread as described in detail in the copending United States patent application of Stanley l. Ketterer, William J. Edwards, and Michael F. Ivanko, Serial No. 12,828, tiled March 4, 1960.

For an understanding of the present invention, the following brief description of the sewing machine, the bobbin thread replenishing mechanism and the thread severing mechanism will suffice.

The sewing machine frame includes a base 11 from which extends a work supporting arm 12 and a vertical standard 13 supporting a bracket arm 14 overhanging the Work supporting arm. The sewing machine frame base 11 is carried on a subbase 15 in which is journaled a pattern cam 16 for controlling not only the pattern of stitches to be produced but also the operation of the under or bobbin thread replenishing mechanism and the number of stitches to be formed in each sewing operation. Journaled in the bracket arm 14 is a main shaft 17 having fast thereon a sprocket wheel 18 drivingly engaging a timing belt 19 meshing with a sprocket wheel 20 fast on a hollow loop-taker drive shaft 21 journaled in the work supporting arm. The main drive shaft, by way of a worm 22 and a worm wheel 23 on a vertical cam shaft 24 journaled in the standard, drives the pattern cam 16. In the bracket arm 14, a compound crank 25 serves by way of a drive link 26 to impart endwise reciprocatory motion to a needle bar 27 which is journaled in the bracket arm and carries an eye pointed needle 28. The crank 25 serves by way of a drive link 29 to impart oscillatory motion to a needle thread take-up lever 30 fulcrumed on the bracket 31 and formed on its free extremity with a thread accommodating eyelet 32. The take-up lever Sti moves rela-tively to a pair of thread guides 33 and 34 fixed relatively to the bracket arm and between which the take-up lever serves to expand and slacken a loop of thread which extends from a supply (not shown) to the needle 2S.

Fast on the loop-taker drive shaft 21 so as to partake of a rotary motion in cooperation with the needle 28 suitable for the formation of lock stitches is a loop-taker indicated generally as liti. Referring to FIG. 2, the looptaker includes a cup-shaped body portion 41 formed with a needle loop seizing beak 42, and a bobbin carrying case i3 journaled within the body portion of the loop-taker but constrained from rotation therewith by means of a rotating restraining finger 44. In sewing, the beak 42 of the loop-taker serves to seize and carry loops of needle thread completely about the bobbin carrying case t3 and about a bobbin 45 which is journaled freely in the bobbin carrying case. A bobbin winding member 46 in disposed within the cup-shaped loop-taker body portion and is formed with a gripping arm 47 which serves to clamp to the loop-taker beak a loop and needle thread seized thereby. The loop of needle thread clamped on the beak by the gripping arm 47 will continue to be gripped thereon while the bobbin is replenished with thread from the needle. The above referred to copending United States patent application Serial No. 15,955 may be referred to for a more detailed explanation of the operation of the bobbin thread replenishing mechanism. When the bobbin winding member 46 is retracted to discontinue bobbin replenishment and to begin the formation of stitches, the tag end of the thread loop which had been gripped on the loop-taker beak 4t2 by the gripping arm 47 will be released. This released tag end of thread will eventually be carried into the bobbin by the turning movement of the loop-taker relatively to the bobbin but if the tag end of thread is too long when first released there is a danger that before it can be carried into the bobbin it might be drawn into the seam being stitched thus causing improper stitch formation. It is the purpose of this invention to provide a novel and effective means for shortening this tag end of thread so as to prevent any possibility of its being caught up in the stitched seam.

Indicated generally at 5t) is a thread severing mechanism carried by the work supporting arm 12 of the sewing machine frame which serves, as described in detail in the above referenced copending United States patent application Serial No. 12,828, to sever closely adjacent to the work both of the sewing threads, i.e., that from the needle and that from the under or locking thread on the bobbin. The thread severing mechanism is preferably actuated by the operator-induenced lever 15 on the standard simultaneously with the raising of a work clamp 52 when the machine has come to rest at the completion of a cycle of operation.

The operation of the sewing machine is controlled by a stop motion mechanism indicated generally as 60. The stop motion mechanism includes a separable frictional driving device comprising axial separable V-belt pulley halves 61 and 62 of which pulley half 61 is axially slidable and freely journaled on the main shaft and the pulley half 62 is secured for rotation with the main shaft 17. An arm 63 carried by a swinging stop motion control frame 64 fulcrumed on the standard at 65 serves to urge the pulley halves together into machine driving relation or to permit separation of the pulley halves to declutch the machine from a driving motor (not shown). The stop motion also includes a positive stop means for the main shaft 17 comprising a stop arm 66 journaled relatively to the main shaft 17 and slidable axially thereof, which cooperates with a stop notch 67 formed in the hub 68 of the pulley half 62 which is fixed for turning movement with the main shaft 17. The stop arm 66 is carried axially of the main shaft into and out of locking engagement with the stop notch 67 by the control frame 64. A plunger 69 is pivoted to the stop arm 66 and loosely guided in a sleeve '70 on the control frame 64. Carried on the plunger 69 between the sleeve 7G and the stop arm 66 are a plurality of flexible washers 71, and carried on the plunger at the opposite side of the sleeve 70 are a plurality of similar flexible washers 72. A pair of lock nuts 73 carried on the free extremity of the plunger serves to constrain the washers 7l and 72 in place on the plunger.

The problem to the solution of which this invention is directed is that the length of thread extending from the needle to the point at which the thread is severed from the work by the thread severing device 56 may not be sufiiciently short as is desirable for the proper operation of the bobbin thread replenishing mechanism at the beginning of the succeeding cycle of machine operation. The problem has been solved in this invention by providing means for accurately positioning the take-up lever 30 when the machine is constrained in an at rest position by the stop arm 66. The take-up lever 3@ is in accordance with this invention stopped before it reaches the position of maximum expansion of the thread loop relatively to the fixed thread guides 33 and 34. With reference to FIG. 4, the position of the take-up lever illustrated in solid lines represents that of maximum expansion between the thread guides 33 and 34. In FIG. 4, the position of the take-up lever illustrated in dash-dash lines indicates a typical stop position of the take-up lever in accordance with this invention.

At the beginning of the succeeding cycle of sewing machine operation the take-up lever 30 will immediately move through the position of maximum expansion of the thread loop defined by the thread guides 33 and 34, and in so doing, will draw additional thread from the needle, thus shortening the free end of the thread loop extending from the needle.

By selecting an at rest position of the take-up lever 3f), which is a greater distance from that at which the maximum thread loop is expanded between the thread guides 33 and 34, a correspondingly greater shortening of the length of thread extending from the needle will be accomplished.

With reference to FIG. 3, a preferred manner `of effecting the above described selective at rest position of the take-up lever is by a rearrangement of the ilexible washers 71 and 72 from one side to the other of the sleeve 70. As illustrated in solid lines in FIG. 3, the arrangement of washers 71 and 72 provide for one at rest position of the stop arm 66. The position of parts illustrated in dashed lines in FIG. 3 results from the rearrangement of one of the washers 72 to the opposite side of the sleeve 70, `and a correspondingly greater change in the at rest position of the stop arm 66 lnay be effected by rearranging a greater number of the washers or by substituting washers of different dimensions.

Having thus set forth the nature of this invention, what is claimed herein is:

l. In a lock stitch sewing machine having a frame, a thread carrying needle, a needle thread take-up, and a loop-taker carried by said frame, actuating mechanism operatively connecting said needle, take-up and loop-taker for movement in timed relation suitable for the formation of lock stitches, a thread carrying bobbin journaled in said loop-taker, a stop motion mechanism associated with said actuating mechanism including a separable friction drive device for driving said actuating mechanism and a stop means engageable between said actuating mechanism and said frame defining `a predetermined stopped position of said actuating mechanism, in combination needle thread severing means effective during engagement of said stop means for severing said needle thread extending from said needle to the lock stitches, means associated with said loop-taker and effective during operation of said actuating mechanism for gripping on said loop-taker the end of thread extending from said needle severed by said last mentioned means, means for winding on said bobbin the thread gripped on said loop-taker by said thread gripping means, and means for shortening the severed end of thread extending from said needle prior to operation of said thread gripping means, said thread shortening means comprising means for positioning said needle thread take-up in a selected one of a range of positions upon engagement of said stop means.

2. In a lock stitch sewing machine having a frame, a thread carrying needle, a needle thread take-up, and a loop-taker carried by said frame, actuating mechanism operatively connecting said needle, take-up, and looptaker for movement in timed relation suitable for the formation of lock stitches, a thread carrying bobbin journaled in said loop-taker, a stop motion mechanism associated with said actuating mechanism including a separable friction drive device for driving said actuating mechanism and a stop means Iengageable between said actuating mechanism and said frame defining a predetermined stopped position of said actuating mechanism, in combination needle thread severing means effective during engagement of said stop means for severing said needle thread extending from said needle to the lock stitches, means associated with said loop-taker and effective during operation of said actuating mechanism for gripping on said loop-taker the end of thread extending from said needle severed by said last mentioned means, means for winding on said bobbin the thread gripped on said loop-taker hy said thread gripping means, and means for positioning said needle thread take-up in a selected one of a range of positions upon engagement of said stop means to eifect shortening of the severed end of thread extending from said needle prior to operation of said thread gripping means, said take-up positioning means comprising means for positioning said stop means of said stop motion mechanism in selected position relatively to said sewing machine frame.

3. In a lock stitch sewing machine having a frame, a thread carrying needle, a needle thread take-up mechanism including a pair of thread guides fixed relatively to said frame and a thread engaging take-up member supported on said frame `for movement in a closed path relatively to said fixed thread guide alternately to draw out to a predetermined maximum length and to collapse a loop of thread between said fixed thread guides, and a loop-taker carried by said frame, actuating mechanism operatively connecting said needle thread engaging take-up member and loop-taker for movement in timed relation suitable for the formation of lock stitches, a third carrying bobbin journaled in said loop-taker, a stop motion mechanism associated with said actuating sneer/1s 5 mechanism including a separa-ble friction drive means for driving said actuating mechanism and a stop means engageable between said actuating mechanism and said frame defining a predetermined stopped position of said actuating mechanism, in combination needle thread severing means effective during engagement of said stop means for severing said needle thread extending from said needle to the lock stitches, means associated with said loop-taker and eiective during operation of said actuating mechanism for gripping on said loep-taker the end of thread extending from said needle severed by said last mentioned means, means for Winding on said bobbin the thread gripped on said loop-taker by said thread gripping means, and means for shortening the severed end of thread extending `from said needle prior te References Cited in the file of this patent UNITED STATES PATENTS 1,794,255 Stephensen Feb. 24, 1931 2,825,296 Sweet et al. Mar. 4, 1958 FOREIGN PATENTS 1,224,744 France Feb. S, 1960 

